|Park, Chul Hwi|
Submitted to: Water Environment Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2002
Publication Date: 3/1/2003
Citation: Kim, H., Murtry, S., Peot, C., Ramirez, M., Strawn, M., Park, C., McConnell, L.L. 2003. Examination of mechanisms for odor compound generation during lime stabilization. Water Environmental Research. 75(2):121-125. Interpretive Summary: Based on the results from the full-scale and lab scale studies, it has been observed that trimethylamine (TMA) and dimethyldisulfide (DMDS) are two main odor compounds released during lime stabilization of biosolids from wastewater treatment plants. There are several important factors involved in TMA and DMDS production in the stabilization process: protein content of sludge feed, polymer usage, storage prior to liming and enzyme mediated transformations. Of practical significance for biosolids management, it appears that the generation of TMA cannot be eliminated under the anaerobic conditions normally present during solids processing. Also, liming cannot be ceased, considering its effectiveness in inactivation of microorganisms in biosolids. Management practices can be developed to minimize production, i.e., limiting the use of cationic polymers. Limiting storage prior to liming may also reduce TMA production significantly. In the future, strategies to limit the enzymatic breakdown of proteins and polymers into odorous products should be investigated. Additionally, methods to alter the precursors formed should be evaluated. Additionally, more research is needed to determine the physico-chemical role of lime in TMA formation. Although further study is needed to address odor mitigation during the lime stabilization as addressed above, this work itself is enough to give operators and engineers important information on arriving at methods to control TMA release from the plant.
Technical Abstract: Lime stabilized biosolids produced from a wastewater treatment plant can often emit odors, especially 'fishy' and 'decaying' odors. These odors can generate public opposition to biosolids land application programs, although it is an environmentally friendly recycling of organic material that is beneficial to agricultural industry. Therefore, it is critical to examine the controlling factors involved in odor production during the lime stabilization process. Results from preliminary experiments examining added polymer and protein material to de-watered limed biosolids show increased TMA production with further increases with 1 hour and 4 hour storage times prior to liming. Further experiments with water/silica slurry reaction media reveal that enzymatically-facilitated degradation of polymer and protein is the over-riding factor in TMA and DMDS production. It is hypothesized that macromolecules like polymer and proteins in biosolids are first broken down enzymatically, following which, the addition of lime causes TMA and DMDS to be released.